Maybe I just understand the word "monolith" differently. I understand it as an application that cannot be easily broken to pieces that run on different machines. So the only option is to scale horizontally, if at all.
What I mean is that you can e.g. run two monoliths on two machines, and process half of your users at the 1st machine, and the 2nd half of your users at the 2nd machine. If the users don't need to interact (or in a limited way, for instance, you need to recalculate something each day or so), it's a good enough solution just using horizontal scaling.
What I mean is that you can e.g. run two monoliths on two machines, and process half of your users at the 1st machine, and the 2nd half of your users at the 2nd machine. If the users don't need to interact (or in a limited way, for instance, you need to recalculate something each day or so), it's a good enough solution just using horizontal scaling.